Multiple Versions of Python on Windows XP

Could anyone please point me to
documentation on the way the msi
installer handles multiple versions eg.
Python 2.5, 2.6 and 3.0?

What changes are made to the registry?

Is there some way to specify a default
version in such a way that it can be
changed as necessary?

PyScripter uses an option to select a
version eg.

C:\Program
Files\PyScripter\PyScripter.exe --python26

but I'm having some trouble with it when
I attempt edit a python file from the
Windows Explorer.

I would appreciate any information.

Colin W.

> Could anyone please point me to documentation on the way the msi
> installer handles multiple versions eg. Python 2.5, 2.6 and 3.0?

I don't think that is documented anywhere.

> What changes are made to the registry?

For a complete list, see Tools/msi/msi.py in the source tree.

> Is there some way to specify a default version in such a way that it can
> be changed as necessary?

What do you mean by "default version"?

There is the version that is associated with the .py/.pyc extensions
at any point in time; you can change these by re-running the respective
installers from add-and-remove-programs. In a well-managed installation,
only one Python installation would have the "Register Extensions"
feature selected; to then change the default, one would unselect the
feature in one version, and reselect it in a different. If only the
default installation procedure was ever used, re-running the installer
in "Repair" mode (from ARP) will also restore the extension
associations.

> PyScripter uses an option to select a version eg.
>
> C:\Program Files\PyScripter\PyScripter.exe --python26
>
> but I'm having some trouble with it when I attempt edit a python file
> from the Windows Explorer.

It would be good to be more specific with such statements: what troubles
specifically? If I play dumb, I'd say "of course - windows explorer
doesn't support editing Python files; you need a text editor".

Regards,
Martin

On approximately 12/1/2008 11:05 PM, came the following characters from
the keyboard of Martin v. Löwis:
>> Is there some way to specify a default version in such a way that it can
>> be changed as necessary?
>>
>
> What do you mean by "default version"?
>
> There is the version that is associated with the .py/.pyc extensions
> at any point in time; you can change these by re-running the respective
> installers from add-and-remove-programs. In a well-managed installation,
> only one Python installation would have the "Register Extensions"
> feature selected; to then change the default, one would unselect the
> feature in one version, and reselect it in a different. If only the
> default installation procedure was ever used, re-running the installer
> in "Repair" mode (from ARP) will also restore the extension
> associations.

That seems a lot more cumbersome than just using the command line to
change the ftype and assoc a bit. Here's how I set up my computer, for
multiple versions. Now to change the "default", I just use the assoc
command to change the association for .py to one of the three listed
ftypes. Simple and quick.

c:\>ftype Python25.File
ftype Python25.File
Python25.File="C:\Python25\python.exe" "%1" %*

c:\>ftype Python26.File
ftype Python26.File
Python26.File="C:\Python26\python.exe" "%1" %*

c:\>ftype Python30.File
ftype Python30.File
Python30.File="C:\Python30\python.exe" "%1" %*

c:\>assoc .py
assoc .py
..py=Python25.File


It would be nice if the ftypes were version specific as created by the
installer; IIRC, I created the above three from the ftype Python.File as
I installed each version.

--
Glenn -- http://nevcal.com/
===========================
A protocol is complete when there is nothing left to remove.
-- Stuart Cheshire, Apple Computer, regarding Zero Configuration Networking

> It would be nice if the ftypes were version specific as created by the
> installer; IIRC, I created the above three from the ftype Python.File as
> I installed each version.

That's a good idea; please submit a wish list item to bugs.python.org.
There may be issues (such as people relying on this being Python.File),
but I can't see any problems off-hand.

Regards,
Martin

On approximately 12/1/2008 11:29 PM, came the following characters from
the keyboard of Martin v. Löwis:
>> It would be nice if the ftypes were version specific as created by the
>> installer; IIRC, I created the above three from the ftype Python.File as
>> I installed each version.
>>
>
> That's a good idea; please submit a wish list item to bugs.python.org.
> There may be issues (such as people relying on this being Python.File),
> but I can't see any problems off-hand.
>
> Regards,
> Martin
>

OK, Issue 4485 created. My first one, so let me know if I goofed. I
elaborated a bit from the original email, upon reflection. Seemed
useful, but also seemed complex by the time I got done.

I don't really have a clue what the uninstaller should do with these;
nor have I fiddled to know if it presently removes Python.File. I
suppose it should delete them, if and only if the ftype and assoc have
the same content as was created by the corresponding version installation.

--
Glenn -- http://nevcal.com/
===========================
A protocol is complete when there is nothing left to remove.
-- Stuart Cheshire, Apple Computer, regarding Zero Configuration Networking

> OK, Issue 4485 created. My first one, so let me know if I goofed. I
> elaborated a bit from the original email, upon reflection. Seemed
> useful, but also seemed complex by the time I got done.

Looks about right to me.

> I don't really have a clue what the uninstaller should do with these;
> nor have I fiddled to know if it presently removes Python.File. I
> suppose it should delete them, if and only if the ftype and assoc have
> the same content as was created by the corresponding version installation.

The uninstaller will currently just remove it all. Conditional removal
of the associations will be tricky; I'll look into it.

I also wonder whether assoc only changes the settings for the current
user. In that case, uninstalling a Python version that was per-machine
would not affect the user's association, anyway.

Regards,
Martin

Martin v. Löwis wrote:
>> Could anyone please point me to documentation on the way the msi
>> installer handles multiple versions eg. Python 2.5, 2.6 and 3.0?
>
> I don't think that is documented anywhere.
>
>> What changes are made to the registry?
>
> For a complete list, see Tools/msi/msi.py in the source tree.

I have scanned the file:
http://svn.python.org/projects/pytho...ols/msi/msi.py

I don't find anything that addresses
this issue.

>
>> Is there some way to specify a default version in such a way that it can
>> be changed as necessary?
>
> What do you mean by "default version"?

I am seeking some mechanism such that
any of Python 2.5, Python 2.6 or Python
2.6 can be chosen as the currently
active version.

>
> There is the version that is associated with the .py/.pyc extensions
> at any point in time; you can change these by re-running the respective
> installers from add-and-remove-programs. In a well-managed installation,
> only one Python installation would have the "Register Extensions"
> feature selected; to then change the default, one would unselect the
> feature in one version, and reselect it in a different. If only the
> default installation procedure was ever used, re-running the installer
> in "Repair" mode (from ARP) will also restore the extension
> associations.

I was hoping that there is some simpler
way than the "Repair" procedure.

>
>> PyScripter uses an option to select a version eg.
>>
>> C:\Program Files\PyScripter\PyScripter.exe --python26
>>
>> but I'm having some trouble with it when I attempt edit a python file
>> from the Windows Explorer.
>
> It would be good to be more specific with such statements: what troubles
> specifically? If I play dumb, I'd say "of course - windows explorer
> doesn't support editing Python files; you need a text editor".

Yes, I should have been clearer. The
PyScripter application locks up and must
be killed, using the Task Manager.

Many thanks for your response.

Best wishes,

Colin W.
>
> Regards,
> Martin

>>> What changes are made to the registry?
>>
>> For a complete list, see Tools/msi/msi.py in the source tree.
>
> I have scanned the file:
> http://svn.python.org/projects/pytho...ols/msi/msi.py
>
> I don't find anything that addresses this issue.

Read the add_registry function. You may need to first understand
how the Registry table in an MSI file works.

> I am seeking some mechanism such that any of Python 2.5, Python 2.6 or
> Python 2.6 can be chosen as the currently active version.

If Glenn Lindermann's answer doesn't help, you need to explain:
what is a "currently active version"? How is one Python version
more active than any other?

> I was hoping that there is some simpler way than the "Repair" procedure.

See Glenn Lindermann's answer.

>> It would be good to be more specific with such statements: what troubles
>> specifically? If I play dumb, I'd say "of course - windows explorer
>> doesn't support editing Python files; you need a text editor".
>
> Yes, I should have been clearer. The PyScripter application locks up
> and must be killed, using the Task Manager.

I think you need to report that to the PyScripter authors as a bug.
I can't imagine how the "currently active version" can affect what
PyScripter does.

Regards,
Martin

Martin v. Löwis wrote:
>>>> What changes are made to the registry?
>>> For a complete list, see Tools/msi/msi.py in the source tree.
>> I have scanned the file:
>> http://svn.python.org/projects/pytho...ols/msi/msi.py
>>
>> I don't find anything that addresses this issue.
>
> Read the add_registry function. You may need to first understand
> how the Registry table in an MSI file works.
>
>> I am seeking some mechanism such that any of Python 2.5, Python 2.6 or
>> Python 2.6 can be chosen as the currently active version.
>
> If Glenn Lindermann's answer doesn't help, you need to explain:
> what is a "currently active version"? How is one Python version
> more active than any other?
>
>> I was hoping that there is some simpler way than the "Repair" procedure.
>
> See Glenn Lindermann's answer.

I'll look at it
>
>>> It would be good to be more specific with such statements: what troubles
>>> specifically? If I play dumb, I'd say "of course - windows explorer
>>> doesn't support editing Python files; you need a text editor".

Using a right click, one can open any
..py file with say SciTe. Within SciTe,
one can Run the current file.

It would be good to have the appropriate
version (my use of "default") preselected.

>> Yes, I should have been clearer. The PyScripter application locks up
>> and must be killed, using the Task Manager.
>
> I think you need to report that to the PyScripter authors as a bug.
> I can't imagine how the "currently active version" can affect what
> PyScripter does.

Yes, I'll do that.

>

I'll also follow up with Glenn
Lindermann's answer.

Many thanks,

Best wishes,

Colin W.
> Regards,
> Martin

> Using a right click, one can open any .py file with say SciTe. Within
> SciTe, one can Run the current file.
>
> It would be good to have the appropriate version (my use of "default")
> preselected.

I don't know how SciTe choses the version of Python to run. In the
sense in why you use the word, there might just not be a "default"
version of Python on Windows. Somebody who knows SciTe better may
correct me.

Regards,
Martin